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Main Authors: Huynh, Dinh Tuan, Linh, Tran N. K., Long, Le Ngoc
Format: Preprint
Published: 2024
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Online Access:https://arxiv.org/abs/2410.05029
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author Huynh, Dinh Tuan
Linh, Tran N. K.
Long, Le Ngoc
author_facet Huynh, Dinh Tuan
Linh, Tran N. K.
Long, Le Ngoc
contents We study the Waldschmidt constant of some configurations in the projective plane. In the first part, we show that the Waldschmidt constant of a set $\mathbb{X}$ of $n$ points where at least $n-3$ points among them lie on a line is either equal to $1, \frac{2n-3}{n-1}, 2, \frac{16}{7}, \frac{7}{3}, \frac{17}{7},$ or $\frac{5}{2}$. Together with the Hilbert polynomials, this gives a complete geometric characterization for $\mathbb{X}$. Next, we study some specific configurations whose Waldschmidt constants are bounded from above by $\frac{5}{2}$. Under this condition, we describe all configurations of $n$ points with $n-1$ points among them lying on an irreducible conic, and we also study some specific configurations of $9$ points.
format Preprint
id arxiv_https___arxiv_org_abs_2410_05029
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Some line and conic arrangements and their Waldschmidt constants
Huynh, Dinh Tuan
Linh, Tran N. K.
Long, Le Ngoc
Combinatorics
Algebraic Geometry
We study the Waldschmidt constant of some configurations in the projective plane. In the first part, we show that the Waldschmidt constant of a set $\mathbb{X}$ of $n$ points where at least $n-3$ points among them lie on a line is either equal to $1, \frac{2n-3}{n-1}, 2, \frac{16}{7}, \frac{7}{3}, \frac{17}{7},$ or $\frac{5}{2}$. Together with the Hilbert polynomials, this gives a complete geometric characterization for $\mathbb{X}$. Next, we study some specific configurations whose Waldschmidt constants are bounded from above by $\frac{5}{2}$. Under this condition, we describe all configurations of $n$ points with $n-1$ points among them lying on an irreducible conic, and we also study some specific configurations of $9$ points.
title Some line and conic arrangements and their Waldschmidt constants
topic Combinatorics
Algebraic Geometry
url https://arxiv.org/abs/2410.05029